Viscoelastic Focusing of Living Cells: Fluidic Mechanics Insights for Microfluidic Device Design

This study presents an experimental investigation of viscoelastic focusing on living cells, with a specific emphasis on viscoelasticity influence. Experiments were conducted in straight microchannels with a rectangular cross-section (WXH= 34.5 X 80 μm and 80 X 34.5 μm), exploring a wide range of Reynolds numbers (Re = 0.01 to 44), viscoelasticity (EI = 0.36 to 1.7), and shear thinning effects of carrier fluids to study their impact on cell-focusing behaviors. The extensive dataset obtained from our high-speed video-collecting apparatus (400 to 30,000 fps and 100,000+ frames per condition) allowed for a meticulous single-cell level analysis of the interplay between fluid inertia and viscoelastic characteristics. The investigation yields crucial design guidelines for microfluidic devices that effectively leverage viscoelastic focusing for label-free cell purification and flow cytometry. This work serves as a critical resource for researchers and practitioners aiming to optimize microfluidic devices for cell manipulation and various fluidic mechanics-based applications.